DESCRIPTION: (provided by the applicant): This proposal continues the re-evaluation of the roles of ecdysterolds and juvenile hormones (JH) in vitellogenesis in female Drosophila melanogaster Initiated during the original granting period (NIH GM/0D54905). Our recent work has demonstrated that JHs may be involved in the regulation of early yolk protein (YP) synthesis by follicle cells of the developing egg chamber. However, in apterous mutant, and in diapausing females, vitellogenesis can occur in the absence of JHs, but never in the absence of ecdysterolds. These observations support the model for the endocrine regulation of YP synthesis and uptake (Richard et al., 1998, 2001a). This proposal studies the levels of production and action of ecdysteroids, juvenile hormones, sex peptide and yolk proteins (YPs) by wild-type Canton-S females, Canton-S females in diapause, apterous and apterous, mutants. A successful goal of the previous granting period was to examine the processes of receptor mediated endocytosis in the trafficking of early YPs from the follicle cells, and late YPs from the hemolymph into the developing oocytes (Richard et al., 2001b). We now propose to examine further the mechanisms by which the production of the proteins alpha-adaptin, clathrin and the YP-receptor may be controlled. A cell contact regulatory mechanism between the oocyte and the nurse cells, or between the border follicle cells and both oocyte and nurse cells, is postulated and will be examined initially by immunocytochemical means. Expressed sequence tag micro-array analysis of gene expression patterns in ovaries following treatment with JHs and ecdysterolds is proposed as a simple initial step towards the incorporation of micro-array technology into our laboratory. The significance of these experiments lies with the unique position that D. melanogaster occupies in biological research as both a model insect and a model dipteran. No other insect is as well characterized In terms of its genetic make-up and while It is small, It has proved possible to surgically dissect and manipulate the organs Involved In the endocrine system. Given the Importance of some cyclorrhaphous dipteran species as vectors of human disease, it is of obvious importance that we understand the role of the endocrine system in the regulation of reproductive development.